Amphiphysin 1 is localized on the cytoplasmic surface of synaptic vesicles. Amphiphysin is highly enriched in nerve terminals, where it plays a role in clathrin-mediated endocytosis. Amphiphysin forms a dimer that binds to dynamin and synaptojanin through its carboxy-terminal SH3 domains. This association is believed to be essential for synaptic vesicle recycling in neurons. Amphiphysin is the dominant autoantigen in paraneoplastic Stiff-Man syndrome.